1. Field of the Invention
The invention relates to a fuel injection valve for electrically controlling a fuel whose pressure was raised by a fuel pump and for supplying the fuel to an engine and, more particularly, to a filter which is arranged in a fuel injection valve in order to remove a foreign matter in a fuel passing in a fuel injection valve.
2. Related Background Art
The first example of a filter in a conventional fuel injection valve is shown in FIG. 13. In the following description, a rear edge A indicates an upper portion in the diagram and a front edge B indicates a lower portion. They are used for easily understand an explanation.
Reference character N denotes a fuel injection valve comprising the following component elements.
Reference numeral 30 denotes a cylindrical housing. A fuel pipe 31 made of a metal material is formed so as to be projected from the center of a rear edge 30A of the housing 30 further toward the rear edge A side. An O ring groove 31D is formed around an outer periphery 31C of the fuel pipe 31. An elastic ring R made of a rubber material is arranged in the O ring groove 31D.
On the inside of the housing 30, there are provided: a fixed core 32 which is formed integratedly with the fuel pipe 31, a coil bobbin 34 around which a coil 33 is wound and which is arranged in the outer periphery of the fixed core 32, a movable core which is movably arranged so as to face the fixed core 32, and a valve body which is moved synchronously with the movable core and opens and closes a valve hole that is opened toward a front edge 30B of the housing 30. The movable core, valve hole, and valve body are not shown. A fuel pipe 35 is formed in the fuel pipe 31 so as to be directed from a rear edge surface 31A toward the valve hole side. The fuel pipe 35 penetrates in the fuel pipe 31 and fixed core 32 and is opened inwardly of the housing 30.
A cylindrical filter 36 is arranged in the fuel pipe 35. An annular collar member 37 made of a metal material is arranged on the outer periphery on the rear edge A side of the filter 36. A channel 36C is formed in the filter 36 from a rear edge surface 36A toward a cylinder portion 36B with a bottom on the front edge B side. A slit groove 36D is formed from the channel 36C toward the outer periphery of the filter 36.
A filter net 38 is provided over the slit groove 36D. The filter 36 is inserted with a pressure into the fuel pipe 35 of the fuel pipe 31.
The fuel injection valve N having the filter 36 is sandwiched between a fuel distributing pipe D and an intake pipe (not shown) through an elastic member C. The fuel distributing pipe D has a distributing passage 39 in the longitudinal direction connected to a fuel pump and a fuel injection valve supporting hole 40 which is opened in the distributing passage 39.
The fuel pipe 31 of the fuel injection valve N is inserted into the fuel injection valve supporting hole 40 through an opening edge thereof and is sandwiched between the fuel distributing pipe D and the intake pipe. A hermetical state of a gap formed between the outer periphery 31C of the fuel pipe 31 and the fuel injection valve supporting hole 40 is held by the elastic ring R.
The fuel supplied into the distributing passage 39 of the fuel distributing pipe D by the fuel pump flows into the fuel pipe 35 of the fuel injection valve N from the fuel injection valve supporting hole 40. A foreign matter in the fuel in the fuel pipe 35 is removed by the filter net 38 of the filter 36, so that the clean fuel is supplied toward the valve hole in the fuel injection valve N.
The second example of the filter in the conventional fuel injection valve will now be described with reference to FIG. 14. A structure of the filter in the second example differs from that of FIG. 13. Only a filer 41 will now be described.
According to the filter 41, an annular flange portion 41A is formed on the rear edge A side, a cylinder portion 41C is formed from the annular flange portion 41A toward a cylinder portion 41B with a bottom on the front edge B side, and a slit groove 41D is formed in the cylinder portion 41C.
A channel 41E is formed from a rear edge surface 41F of the annular flange portion 41A toward the cylinder portion 41B with the bottom. The slit groove 41D is opened in the cylinder portion 41C so as to face the channel 41E. Further, a filter net 42 is attached over the slit groove 41D.
The cylinder portion 41C of the filter 41 is inserted with a pressure into the fuel pipe 35 of the fuel pipe 31. In this instance, the annular flange portion 41A is arranged so as to be in contact with the rear edge surface 31A of the fuel pipe 31.
According to the conventional first example, when the fuel pipe 31 of the fuel injection valve N is inserted into the fuel injection valve supporting hole 40 of the fuel distributing pipe D, the outer periphery 31C of the fuel pipe 31 on the rear edge surface 31A side of the fuel pipe 31 is come into contact with an entrance portion of the fuel injection valve supporting hole 40, so that there is a fear of occurrence of chips in the contacting portion. This is because a gap for insertion is formed between the outer periphery 31C of the fuel pipe 31 and the fuel injection valve supporting hole 40 and it is apprehended that the fuel pipe 31 is inclined in the gap and is inserted into the fuel injection valve supporting hole 40. This is also because the fuel pipe 31 is generally made of a metal material such as stainless steel or the like and the fuel distributing pipe D is made of a metal material such as aluminum, zinc alloy, or the like, so that both of those metal materials are come into contact with each other.
When the chips enter the elastic ring R arranged between the fuel pipe 31 and fuel injection valve supporting hole 40, the elastic ring R is damaged, so that it is unpreferable.
When the chips enter the filter net 38, the chips are accumulated in the filter net 38 and a filtering area of the filter net 38 is reduced, so that it is undesirable. Further, since the chips collide with the filter net 38 by an inertia force of the rapid fuel flow, there is a fear of damage of the filter net 38.
According to the second conventional example, the filter 41 is made of a synthetic resin material and an outer diameter of the annular flange portion 41A of the filter 41 is set to be larger than a diameter of the outer periphery 31C of the fuel pipe 31. Consequently, when the fuel pipe 31 is inserted into the fuel injection valve supporting hole 40 of the fuel distributing pipe D, the annular flange portion 41A of the synthetic resin material can be come into contact with the entrance portion of the fuel injection valve supporting hole 40, so that the generation of the chips in the contacting portion can be suppressed.
It is, however, difficult to accurately form the outer diameter portion of the annular flange portion 41A at the time of molding formation of the filter 41. It is considered that the reasons of it are because the diameter of the cylinder portion 41C and that of the annular flange portion 41A largely differ and there is a large difference between the areas in the cross sectional surfaces of the cylinder portion 41C and annular flange portion 41A, so that the outer diameter of the annular flange portion 41A is influenced by a deformation of the synthetic resin material at the time of formation.
When the annular flange portion 41A is formed so that its diameter is smaller than that of the outer periphery 31C of the fuel pipe 31, the outer periphery 31C of the fuel pipe 31 is come into contact with the fuel injection valve supporting hole 40, causing an inconvenience similar to that of the first conventional example. When the annular flange portion 41A is formed so as to have a large diameter, it is difficult to insert into the fuel injection valve supporting hole 40.
From the above points, it is necessary to accurately manage the diameter of the annular flange portion 41A, a large number of processing steps are needed for the managing work, and manufacturing costs rise, so that it is unpreferable.